[Form 4] IGM Biosciences, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Topsoe Holding A/S disclosed disposition of all IGM Biosciences shares following a completed merger. Under the Merger, Merger Sub merged into IGM Biosciences on 08/14/2025 and each outstanding share of Common Stock and Non-Voting Common Stock was cancelled and converted into $1.247 in cash plus one contingent value right (CVR) governed by a Contingent Value Rights Agreement. The Form 4 reports Topsoe Holding A/S disposed of 10,400,564 shares of Common Stock and 5,044,295 Non-Voting Common Stock, leaving 0 shares beneficially owned post-transaction. The filing notes certain Topsoe directors may be deemed to share voting and investment power with respect to the reported shares.

Positive

• Completed merger converting equity to cash plus CVRs provides immediate liquidity to shareholders
• Full disclosure of exact share counts disposed: 10,400,564 Common and 5,044,295 Non-Voting Common shares
• CVR structure preserves contingent upside for former shareholders beyond the fixed cash payment

Negative

• Public equity extinguished as IGM became a wholly owned subsidiary, removing publicly traded shares
• Post-transaction ownership reports 0 shares beneficially owned by Topsoe Holding A/S, eliminating direct investor transparency in ongoing company ownership

Insights

M&A Specialist

TL;DR: The Form 4 documents a standard acquisition closing where target equity was cashed out with contingent value rights.

This disclosure confirms consummation of a merger in which IGM Biosciences became a wholly owned subsidiary of Concentra Parent through Merger Sub on 08/14/2025. The merger consideration was a fixed cash component of $1.247 per share plus CVRs, which preserves potential contingent upside for former shareholders. The complete cancellation and conversion of both Common and Non-Voting Common stock to cash and CVRs is material because it extinguishes public equity and transforms former shareholders into CVR holders or cash recipients.

Corporate Governance Expert

TL;DR: Reporting person surrendered all direct holdings; disclosure clarifies potential shared power among Topsoe directors.

The filing shows Topsoe Holding A/S disposed of 100% of its reported IGM equity, now reporting zero beneficial ownership. The explanation also discloses that named Topsoe board members "may be deemed to share voting and investment power" over those shares and disclaim beneficial ownership except for any pecuniary interest. That disclosure is appropriate for entities with shared governance structures and helps to clarify lines of beneficial ownership following the merger transaction.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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X

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Topsoe Holding A/S

(Last) (First) (Middle)

HALDOR TOPSOES ALLE 1

(Street)

KGS. LYNGBY G7 2800

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
IGM Biosciences, Inc. [ IGMS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/14/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/14/2025		D		10,400,564(1)	D	(1)	0	D(2)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Non-Voting Common Stock(3)	(3)	08/14/2025		D			5,044,295(1)	(3)	(3)	Common Stock	5,044,295	$0	0	D(2)

Explanation of Responses:

1. Pursuant to the Agreement and Plan of Merger dated July 1, 2025, by and among IGM Biosciences, Inc. (the "Company"), Concentra Biosciences, LLC, a Delaware limited liability company ("Parent"), and Concentra Merger Sub V, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"), on August 14, 2025, Merger Sub merged with and into the Company (the "Merger"), with the Company continuing as the surviving corporation and a wholly owned subsidiary of Parent. In connection with the Merger, each issued and outstanding share of the Company's Common Stock and Non-Voting Common Stock was cancelled and converted into the right to receive (i) an amount equal to $1.247 in cash and (ii) one contractual contingent value right (a "CVR") subject to the terms and conditions of a Contingent Value Rights Agreement.

2. Prior to the Merger, the shares were held directly by Topsoe Holding A/S. Jakob Haldor Topsoe, Christina Teng Topsoe, Anne Haugwitz-Hardenberg-Reventlow, Emil Oigaard, Thomas Schleicher and Birgitte Nielsen, members of the board of directors of Topsoe Holding A/S, may be deemed to share voting and investment power with respect to the shares reported herein and disclaim beneficial ownership of such shares, except to the extent of his or her pecuniary interest therein, if any.

3. Prior to the Merger, the shares of Non-Voting Common Stock were convertible into the Issuer's Common Stock on a 1-for-1 basis (subject to a 4.99% beneficial ownership limitation that may be increased or decreased by the holder of such shares) and had no expiration date.

	/s/ Henrik Gaarn Bak, Managing Director of Topsoe Holding A/S	08/14/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What did Topsoe Holding A/S report on the Form 4 regarding IGMS?

The Form 4 reports Topsoe Holding A/S disposed of 10,400,564 shares of Common Stock and 5,044,295 Non-Voting Common Stock in connection with the merger on 08/14/2025.

What consideration did former IGM shareholders receive in the merger?

Each cancelled share was converted into $1.247 in cash and one contingent value right (CVR) under a Contingent Value Rights Agreement.

Does Topsoe Holding A/S retain any IGM equity after the transaction?

No. The filing reports 0 shares beneficially owned by Topsoe Holding A/S following the reported transactions.

When was the merger completed according to the filing?

The merger was completed on 08/14/2025, the date the reported dispositions occurred.

Are there disclosures about shared control or related parties?

Yes. The filing states certain Topsoe board members "may be deemed to share voting and investment power" over the reported shares and disclaim beneficial ownership except for any pecuniary interest.